The Scope and Limits of Brain Imaging in Consciousness Research

Hakwan Lau

Brain imaging has gained a lot of attention within the consciousness research community. In this workshop I explain the basic procedures and mechanisms of how a typical fMRI or PET study is done, and how the data are analysed. I then focus on the methodological problems that are often found in published articles, such as statistical problems and anatomical mislocalization. The results in imaging often depend on how the data were analysed, and therefore a cautious reading of the methodology is necessary. I then move on to discuss interpretational issues using examples from the consciousness research literature. I particular pick out cases where theoretical interpretions of brain imaging results were misguided, and explain why some forms of arguments are fallacious. For example, the fact that two tasks reveal similar activations in the same brain region does not mean that they are fundamentally related; there are only so many brain regions defined by conventional labels. I then describe some more advanced methods that bypass the problems discussed. These include repetitional priming, connectivity analyses and multivariate approaches. I also describe new techniques such as MEG and fMRI-guided TMS and discuss how they might contribute to consciousness research in the future.

Abbreviations: fMRI – functional magnetic resonance imaging; PET – positron emission tomography; MEG – magnetoencephalogram; TMS – transcranial magnetic stimulation.

Hakwan Lau 

Short Bio

After I finished my undergraduate thesis in philosophy of mind in Hong Kong, I went to Oxford as a Rhodes Scholar to study the neural mechanisms of volition. There I learned the nuts and bolts of fMRI and TMS. I finished my doctorate in 2004 and since then have been a research fellow at the Wellcome Department of Imaging Neuroscience, where the popular imaging analysis tool SPM is developed. I now work on the neural correlates of visual phenomenality, and I collaborate with experts in imaging methodology (e.g. Karl Friston) to study cortical dynamical interactions using MEG. This year (2005) I won the ASSC William James Prize for contributions to consciousness research.